Spark ignited engines of today use three primary types of ignition systems between the high energy source and the spark plug. In these three systems the coil is positioned away from the spark plug. The spacing assures that the coil is away from the heat source which can damage and destroy the working capability of the coil.
The first system uses an external coil and a spark plug connected by a high voltage wire lead. When these wires age and become worn, the high energy being transmitted from the coil to the plug can escape or not be transmitted. An open high voltage lead can cause misfires and loss of engine efficiency. Further, the escaping energy can be a shock hazard or, if the engine is located in a high fuel environment, may set off an explosion.
A second system includes an integral coil and an elongated spark plug with a threaded connection between the coil and the spark plug. The threaded connection between the coil and the plug requires a critical alignment therebetween. The location of the plug and coil with reference to interference with other engine components such as intake manifolds, exhaust manifolds and valve covers may cause assembly problems. If improperly assembled the threaded connection can become loose due to engine vibration and allow the high energy being transmitted between the coil and plug to escape causing shock hazards and explosions. Moreover, the elongated spark plugs are constructed with an outer metal case causing the plugs to act as a capacitor. The plugs can absorb between 3000 and 4000 volts rather than conducting this energy to the tip of the igniter.
The third system includes an integral coil with a threaded connection, a spark plug and a threaded extender fixedly attached to the coil and the plug. The alignment problem as discussed earlier also exists and the loosening problem is further enhanced because of an added connection. None of the systems as described above provide for a reliable extension between the coil and spark plug.
One invention directed to overcoming some of the problems set forth above is described in U.S. Pat. No. 4,715,337 (DISCLAIMED), which patent issued to Bohl et al. on Dec. 29, 1987. The '337 patent describes a variable length extender. However, the biasing means of the '337 extender is primarily located in a central portion of the length of the extender, which is also the portion of the extender having the least diameter. Therefore, when the extender is compressed in use, because the central portion of the extender does not have a rigid core running therethrough and is also of a relatively small diameter, the extender is susceptible to bending in this central portion. If the extender does bend, the electrical conducting internal members of the extender are brought closer to the wall of the spark plug well and it becomes more probable that the electrical potential on the central conductor will pierce the insulator and arc over to the wall and short circuit the system. Further, when bent, the insulator of the extender may crack, creating an opening for the electricity to arc with the wall of the spark plug well.
The present invention is directed to overcoming one or more of the problems as set forth above.